Four men sentenced to death for the gruesome gang rape and murder of a woman on a New Delhi bus in 2012 were hanged Friday, concluding a case that exposed the scope of sexual violence against women in India and prompted horrified Indians to demand swift justice.

The men were hanged at Tihar Jail in New Delhi, Press Trust of India reported, quoting jail authorities.

The victim, a 23-year-old physiotherapy student, was heading home with a male friend from a movie theater when six men tricked them onto a private bus. With no one else in sight, they beat her friend and repeatedly raped the woman. They penetrated her with a metal rod, causing fatal internal injuries. They dumped both victims on the roadside, and the woman died two weeks later.

The case drew international attention and prompted Indian lawmakers to stiffen penalties for rape, part of a wave of changes as India confronted its appalling treatment of women.

Facing public protests and political pressure after the attack, the government reformed some of India's antiquated laws on sexual violence and created fast-track courts for handling rape trials that formerly could last more than a decade.

Asha Devi, the mother of the victim, thanked the judiciary and government after the convicts were hanged.

"Today, we got justice and this day is dedicated to the daughters of the country," she told reporters. "I could not protect her but I was able to fight for her."

Devi said she hoped that courts in India will end delays in rape cases and punish convicts within a year's time.

Hundreds of police were deployed outside the jail to control a crowd that waited to celebrate the executions. Dozens of activists and commoners held placards hailing the hangings outside the jail premises. The crowd chanted slogans like "Justice for women" in favor of the hangings and cheered by clapping and blowing whistles.

The assailants had stood trial relatively quickly in India's slow-moving justice system. Four defendants were found guilty and sentenced to death in 2013 and India's top court upheld the decisions in 2017.

Another suspect had hanged himself in prison before his trial began, though his family insists he was killed. The sixth assailant was a minor at the time of the attack and served three years in juvenile detention.

The executions were carried out as two recent attacks renew attention to the problem of sexual violence in India.